Safety PLC

[KrabbyPatty]

Hello, I have been programming with Logix for over 2 years now, my current job just put me on a job where we had to change some of our original PLC safety routines. We are now needing to you CROUT, DSF, and DCSTL..

We have not worked with this.. and in my years these function blocks have not been used by me.

Can you guys give me some insiders on them? I am having some trouble with the DCSTL and CROUT. Just understanding different parts of them and specific functions...and what I am doing wrong for it to not function correctly.

 

[dmroeder]

Welcome to the forum. The help files are actually pretty good if you haven't looked at them. Plunk one on a rung, select it and press F1. The timing diagrams are helpful. Post back with specific questions.

 

[KrabbyPatty]

Thank you dmroeder! Yes, I have been reading through the help for both of them. I am mainly focusing on the DCSTL right now... most of it makes sense but there is something going on that is not registering my door sequence to reset to not be faulted and now the .FP is not going away. I have not done anything besides look at the manuals and examples for the CROUT function.

But I wanted to ask in here just incase one of you might have some extra tips or things to say...because the help has done as much as it can for me and some colleagues.

 

[ASF]

Check the fault code and diagnostic code of the DCSTL/CROUT instructions, and read the help files for an explanation. That will generally tell you the exact nature of the problem.

I've actually got AOI's and SCADA faceplates to read those codes and convert them to a human-readable explanation of the fault e.g. "Channel A turned off while Channel B remained on" or "safety contactor feedback did not change state within the required time" or "guard unlocked while hazard still present". So I've trawled through the diagnostic and fault codes in quite a bit of detail, and found them (and the help files) to be very comprehensive.

 

[dmroeder]

For clarity, my comment wasn't intended to be condescending. You're not indicating that you felt that way, I just wanted to be sure. Sometimes the help files are overlooked.

If you look at the tag in tag database, check .FaultCode. Then in the help file, you can see what the fault description is and hopefully a corrective action. What fault code do you have?

 

[JaxGTO]

You can also put the instruction CROUT in the knowledge base and it has lots of information.
Also try googling it. Amazing how much info I get from google.

 

[Jeev]

It's important to note that some instructions require the Actuate or ChA/ChB to go low or go low and high again before they will let you clear certain .FP's.

What are the specific faults you are getting?

 

[JeremyM]

If you’ve worked with safety relays like a 440R then something like the CROUT will make intuitive sense. It accepts the safety function circuit inputs and provides a diagnostic feedback and safety function outputs. It will also exhibit the same reset behavior in that the input can’t be held closed.